Knowledge Bank

Using the SeI 1961 {\AA} spectral line to pump the $J=3/2$ component of the $v=3$, $N=1$ level of the NO $A2\Sigma +$ state, we observe the rho-doubling hyperfine transitions and Stark effect by optical radio-frequency double resonance. The following molecular constants are obtained: the rho-doubling constant $\gamma =-82.91\pm 0.03$ MHz; the hyperfine parameters of the $\mathrm{<mrow\; data-mjx-texclass="ORD">14</mrow>}N$ nucleus b = 40.29 $\pm 0.07$ MHz, $c=2.25\pm 0.11$ MHz, and eq $Q=-2.88\pm 0.17$ MHz; and the dipole moment $\mu =1.10\pm 0.03$ D, where all errors represent three standard deviations. The value of $\gamma$ is explained reasonably well by calculations of the A-X spin-orbit mixing, while b and c are within 6% and 18% of recent CI calculations by S. Green. However, the measured dipole moment differs considerably from the CI value, $\mu =0.40\pm 0.10$ D. This discrepancy is not explained by non-adiabatic and relativistic effects omitted from the CI calculation.